NO. 2151. FOSSIL PLANTS FROM FLORISSANT— KNOWLTON. 275 



Cockerell considers Sorhus nwpta to be one of the parents, which, 

 crossed with Sorhus megaphtjUa, Cockerell, has produced a hybrid 

 called Sorhus diversifolia. 



CRATAEGUS, species. 



Plate 21, fig. 4. 



A single segment of a branch 4 cm. in length showing two oppositely 

 inserted leaves (base of petioles alone preserved) and a single strong, 

 sharp thorn 1 cm. in length, near the base. 



Type— Cat. No. 34,763, U.S.N.M. 



This specimen, although a mere fragment, is unmistakably that of 

 Crataegus, as shown not only by the presence of a characteristic thorn, 

 but by the alternate uisertion of the loaves. It is very much io be 

 regretted that only the petioles are preserved, for otherwise it might 

 be possible to connect it with one of the two species already described 

 from the leaves. These are Crataegus lesquereuxi Cockerell {C. acerl- 

 folia Lesquereux, 1883, not Moench, 1785), and C. acutUoha (Les- 

 quereux). It is useless to attem^pt to work out possible affinities 

 between either of the Florissant species and the thousand (more or 

 less) living species now recognized in North America, and even the 

 propriety of givmg a name to such an imcharacteristic portion as a 

 thorny branch, may well be questioned. 



Family RUTACEAE. 



PTELEA MODESTA (Lesquereux) Cockerell. 



Ptelea wiorfesia (Lesquereux) Cockerell, Bull. Amer. Mus. Nat. Hist., vol. 24, 



1908, p. 98. 

 Cj/iisMS mof/es^ifs Lesquereux, Repc. U. S. Geoi. Surv. Terr., vol. 8 (Cret. and 



Tart. FL), 1883, p. 200, pi. 39, figs. 9-11. 

 Legwidnosites serrulatns Lesquereux, Rept. U. S. Geol. Surv. Terr., vol. 8, 1883, 



p. 202. pi. 89, figs. 7, 8. 



Tile Scudder material includes four trifoliolate leaves preserved on 

 two pieces of matrix that apparently belong here. The better of these 

 specimens has three leaflets that exliibit great extremes in size, yet 

 they must all be attributed to the same species, since they are either 

 connected or so lie as to make it practically certain that they were 

 jomed when livmg. The smallest leaf has the leaflets only about 7 

 mm. long and 3 mm. broad; the next in size has them from 17 to 25 

 mm, m length and from 5 to 7 mm. in width, while m the largest leaf 

 the leaflets are from 30 to 40 mm. long and about 10 mm. wid<^. 

 The leaflets in the two smaller leaves are perfectly entire, while iu 

 the other they are entire on one side and provided with a few scat- 

 tered low teeth on the other side. In the leaf not figured, which 

 is about the size of the middle-sized leaf just described, the leaflets 

 are aU entire. 



